PHOENIX — A West Valley Mexican-food restaurant is offering free food and proof of its safety after an E. coli outbreak sickened dozens of patrons.

The owners of Federico’s in Litchfield Park said Tuesday that the chain would serve free meals Sept. 16 and two weeks later 20 percent of the day’s gross will go to the National Kidney Foundation.

Maricopa County’s health department had notified the restaurant at Dysart and Camelback roads that customers had become ill there likely from E. coli in July.

“The county has informed us that there are about 70 people who became ill that are linked to have eaten here,” said Federico’s Attorney, Bill Mulligan. “We do not know anything at this time.

“They’re still investigating and trying to figure it out. It’s very perplexing.”

Three lawsuits have been filed.

The restaurant has passed subsequent inspections and earned the OK to reopen Aug. 5.

Federico’s has been working with Linda Cobb, who is known as the “Queen Of Clean,” to enhance its cleaning protocol. She has given the chain her “seal of approval,” and is encouraging people to go ahead and eat there.

The infection causes vomiting, cramps and kidney failure in some cases.

Sales from Sept. 30 will be donated to the state chapter of the National Kidney Foundation.